I think, in terms of an being an RPG, Fallout: New Vegas is better. However, what Fallout 3 manages to succeed in is atmospheric storytelling. The Capital Wasteland feels way more interesting of a setting to me than the Mojave Wasteland. And while the main quest isn't anything special, some of the side quests in this game are the best in Bethesda's entire catalog. One of my favorite games ever.